Neurologic and Psychiatric Disorders
Status epilepticus
Treat in stages: a benzodiazepine first (lorazepam 0.1 mg/kg IV, max 4 mg; or midazolam 0.2 mg/kg IM if no access), then a second-line load - fosphenytoin 20 mg PE/kg, levetiracetam 40–60 mg/kg, or valproate 20–40 mg/kg. Address hypoglycemia and electrolytes concurrently.
Antiseizure drug traps
Valproate carries hepatotoxicity risk, highest under age 2 and with polytherapy; it is also teratogenic and avoided in females of childbearing potential. Lamotrigine requires slow titration because of serious rash (Stevens-Johnson syndrome), and the titration is halved when valproate is coadministered. Carbamazepine is associated with HLA-B*1502 and severe cutaneous reactions in patients of Asian ancestry; oxcarbazepine causes hyponatremia. Phenytoin shows zero-order kinetics, so small dose increases can produce disproportionate level rises.
Psychiatric pharmacotherapy
Stimulants (methylphenidate, amphetamines) are first-line for ADHD; obtain baseline cardiac history, monitor growth, and counsel on abuse potential. Atomoxetine takes 4–6 weeks and carries a suicidality warning. Fluoxetine is approved for depression from age 8; all SSRIs carry a boxed warning for suicidality, requiring close early follow-up. Risperidone and aripiprazole are used for irritability in autism, with metabolic monitoring.
Worked example
A 20 kg child in convulsive status epilepticus: lorazepam 0.1 mg/kg = 2 mg IV, repeated once after 4–5 minutes if seizures persist; if still seizing, load fosphenytoin 20 mg PE/kg = 400 mg PE at no faster than 3 mg PE/kg/min with cardiac monitoring.